Upper-income taxpayers have paid a growing share of the federal tax burden over the last 25 years. A 2008 study by the Organization for Economic Cooperation and Development, for example, found that the highest-earning 10% of the U.S. population paid the largest share among 24 countries examined, even after adjusting for their relatively higher incomes. “Taxation is most progressively distributed in the United States,” the OECD study concluded.

Meanwhile, the percentage of U.S. households paying no federal income tax has been climbing, and reached 51% for 2009, according to a new analysis by the Joint Committee on Taxation. …